# Category Archives: Number Sense

## 911 math assistance service

A four-year old calling 911 for math assistance. History tells us that zero was invented much later than most of the numbers. It was not even accepted as a number right away. Why should we expect a four-year old to think of it then? And take-aways without context for them? Anyway, this video is cute.… Read More »

## The many faces of multiplication

The following table is not meant to be a complete list of ideas about the concept of multiplication. It is not meant to be definitive but it does include the basic concepts about multiplication for middle school learners. The inclusion of the last two columns about the definition of a prime number and whether or… Read More »

## Test your understanding of irrational numbers

The following is a set of tasks which I think are great questions for assessing understanding of irrational numbers. These tasks were from the study of Natasa Sirotic and Rina Zazkis. The responses were analysed in terms of algorithmic, formal, and intuitive knowledge described at the end of the post. Set A This set of tasks… Read More »

## Bob is learning calculation

Bob is an elementary school student. He is learning to calculate. He just learned about addition and multiplication but there are some things that he doesn’t understand. For example, how come 1+3 = 3 + 1? How can it be the same thought Bob? Every morning I have 1 piece of bread for breakfast while… Read More »